DESCRIPTION: The workers' compensation system is designed to provide health care and compensation to all American workers who suffer injuries or illnesses in the workplace without regard to fault. However, preliminary analysis suggests that only half of injured workers file claims. In light of this fact, we propose research with two key goals: (1) To understand the economic, demographic, and policy factors that cause workers with occupational injuries and illnesses not to file claims; (2) To reassess the adequacy of workers' compensation wage replacement rates, in light of the fact that many workers do not file claims or receive benefits of any kind. Consideration of the first goal reveals the surprising finding that the most vulnerable workers-those with the least alternative insurance against workplace injuries and illnesses-may be the ones least likely to file for workers' compensation. They may face higher costs of filing workers' compensation claims. To pursue the second goal, we calculate the total wages lost over several years as a result of a workplace injury, which we will compare to the benefits paid by workers' compensation. These calculations will include the zero benefits paid to workers who do not file claims. We will use the National Longitudinal Survey of Youth (NLSY), a public-use database sponsored by the United States Department of Labor. Use of the NLSY breaks new empirical ground in two important ways. First, the NLSY is a nationally representative database, containing extensive information on over 4,000 workplace injuries, while previous analyses of workers' compensation filing have been limited to the use of site-, firm-, or region-specific data. Second, the NLSY has longitudinal data on earnings as well as unclaimed injuries, while previous analyses of the adequacy of workers' compensation have been limited to workers who file claims. This research is within NIOSH's NORA priority area of the Social and Economic Consequences of Workplace Injuries and Illnesses.